Seismic Response Control of Offshore Platform Structures with Shape Memory Alloy Dampers     

李宏男何晓宇  霍林生 《中国海洋工程》2005,19(2):185-194

In this study, the seismic response control of offshore platform structures with Shape Memory Alloy (SMA) dampers is investigated. A new SMA damper and its restoring force medel are introduced for the calculation of seismic response reduction. Based on an actual platform structure and its mechanical medel, the parameters which may affect the rate of shock absorption are analyzed, such as the number, position and characteristics of the SMA dampers and the condition of the site where the platform is located. The results show that the SMA damper is an effective control device for offshore platforms and satisfactory control can be achieved by proper selection of the parameters.  相似文献   

全数字十二相稳压稳流微机控制系统     

史重光 《中国海洋大学学报(自然科学版)》1994,(Z2)

提出用于十二相可控整流器的８０９８单片机控制系统的电路原理和软件策略。包括自适应控制算法和触发相序计算在内的多种操作全部用软件实现．与通常的方法相比，此系统的成本更低，动态性能和静态性能更好。  相似文献   

养殖对虾病毒性疾病的细菌并发症防治研究   总被引：1，自引：0，他引：1  

苏国成  陈金翠 《台湾海峡》1996,15(2):200-204

本文研究报道了发病对虾肝胰腺分离菌物敏感性，采用防台细菌人工感染方法进行药物饲料的筛选，在实验室及养殖池中进行药物饲料的防治效果试验。结果表明，在对虾病毒流行期间，采用药物饲料可有效防止对虾爆发性大量死亡，提高对虾存活率。  相似文献   

Robust adaptive control of underactuated ships on a linear course with comfort     

K. D. Do  J. Pan  Z. P. Jiang   《Ocean Engineering》2003,30(17):2201-2225

This paper addresses an important problem in ship control application—the robust stabilization of underactuated ships on a linear course with comfort. Specifically, we develop a multivariable controller to stabilize ocean surface ships without a sway actuator on a linear course and to reduce roll and pitch simultaneously. The controller adapts to unknown parameters of the ship and constant environmental disturbances induced by wave, ocean current and wind. It is also robust to time-varying environmental disturbances, time-varying change in ship parameters and other motions of the ship such as surge and heave. The roll and pitch can be made arbitrarily small while the heading angle and sway are kept to be in reasonably small bounds. The controller development is based on Lyapunov’s direct method and backstepping technique. A Lipschitz continuous projection algorithm is used to update the estimate of the unknown parameters to avoid the parameters’ drift due to time-varying environmental disturbances. Simulations on a full-scale catamaran illustrate the effectiveness of our proposed controller.  相似文献   

Geographical distribution of fish catches and temperature variations in the northeast Atlantic since 1945     

Rögnvaldur Hannesson 《Marine Policy》2007

Warming of the northeast Atlantic is expected to affect the location and productivity of fish stocks. It is examined whether variations in catches of cod, herring, mackerel, anchovy and sardines in the ICES statistical areas are related to variations in ocean temperature. Temperatures at certain locations along the Norwegian coast are taken as proxies for temperatures in the Norwegian Sea and the North Sea. It is found that the catches of cod in the North Sea are inversely correlated with temperature and that recruitment and catches of cod in the Norwegian Sea and the Barents Sea are positively related to temperature. There is also some indication of a positive correlation between temperature and the catches of mackerel in the North Sea and the Norwegian Sea, and between temperature and the catches of sardines in the North Sea.  相似文献   

四阶奇异边值问题无穷多个正解存在性的一个注记     

张若君 《中国海洋大学学报(自然科学版)》2002,32(5):848-852

本文考虑四阶奇异边值问题x( 4 ) =λa(t) f (t,x(t) ) ,0 相似文献   

Effects of chemical ecological adjustment and control experiment on phytoplankton community in the Aoshan Bay     

Chen Bijuan  Zhao Jun  Xin Fuyan  Cui Yi  Guo Feng 《海洋学报(英文版)》2002,21(1):115-123

There is a low nutrient level in the Aoshan Bay. In June 1999, the chemical adjustmentand control experiment was made in the Aoshan Bay. Following tracts investigation was carried out before the experiment and on the 1st, 2nd, 4th, 5th, 6th and 45th day/after the experiment. While the variance of amount of phytoplankton, the replacement of superior species and the species composition of phytoplankton were researched. The results show that the amount of phytoplankton in the Aoshan Bay rises gradually after the experiment. Ceratium macroceros Cleve of pyrophyta was the dominant species before the experiment, its dominant index was 37.7％. Six days after the experiment, its dominant index dropped to 17.6％ . Meanwhile the dominant index of Asterionella japanics Cleve rose from 7.1％ to 39.2％ , it became the first dominant species. Forty-five days after the experiment, the amount of phytoplankton in the Aoshan Bay was 5.15 to 137.32 times more than that in 1997.  相似文献   

Transformation of Lambert Conic Conformal Coordinates from a Global Datum to a Local Datum     

E. Grafarend  F. Okeke 《Marine Geodesy》2007,30(4):297-313

This paper treats the problem of how to transform from global datum, for example, from the International Terrestrial Reference System (ITRS), to a local datum, for example, regional or national, for the practical case of the Lambert projection of the sphere or the ellipsoid-of-revolution to the cone. We design the two projection constants n(ϕ₁, ϕ₂) and m(ϕ₁) for the Universal Lambert Conic projection of the ellipsoid-of-revolution. The task to transform from a global datum with respect to the ellipsoid-of-revolution E_A,B² to local datum with respect to the alternative ellipsoid-of-revolution E_a,b², without local ellipsoidal height, is solved by an extended numerical example. Ideas in this paper could be of interest to those working with maps and coordinates transformation from global geodetic datum to local geodetic datum and vice versa, under the Universal Lambert Conic projection, and applicable to precise positioning and navigation, boundary demarcation and determination in the marine environment.  相似文献   

音响驯化技术在鲤养殖中的实验研究     

田涛  张国胜  张旭光  张秀梅 《中国海洋大学学报(自然科学版)》2007,37(1):83-88

探讨淡水养殖尤其是大水域网箱养鱼中由于投饵方式的不当和投饵量过多导致过剩饵料沉积引起水域环境污染的解决方法。本研究利用鱼类的听觉生物学特性,参考音响驯化技术的有关参数,结合投饵用400 Hz正弦波连续音对鲤(Cyprinus carpioLinnaeus)进行了音响驯化实验。结果表明,最初放声时,实验鱼产生惊愕反应,迅速离声源而去;但驯化6 d后,实验鱼在放声后迅速游向声源,摄食时间由最初的150 s缩短到实验后期的60 s。整个实验阶段放声组与对照组摄食时间差异极显著(P<0.01),摄食率和特定生长率无显著差异(P>0.05)。根据实验鱼的生长参数,求得了参考投饵量曲线和方程。本实验结果为音响驯化技术在淡水鱼养殖中的推广应用提供了基础数据。  相似文献   

EDM高程导线测量中的效率和精度问题探讨     

杨晋强  李辉  李建文 《海洋测绘》2007,27(3):31-33

随着全站仪测角测距精度的提高,在高程联测中,用EDM高程导线测量代替三四等水准测量,成为外业高程测量的重要方法之一。分析了影响EDM高程导线测量精度的因素,讨论了提高EDM高程导线测量精度的办法,提出了效率函数的概念,并以某测区三级GPS大地控制网高程联测数据为例,从精度和效率方面进行了计算对比分析。  相似文献